Classification of Sea Ice Summer Melt Features in High‐Resolution IceBridge Imagery

Abstract

AbstractHigh‐resolution observations of melt ponds (MPs) across the Arctic are lacking, yet essential for understanding the sea ice energy budget and under‐ice ecology. We present a pixel‐based classification scheme to identify undeformed and deformed ice, open water, and light, medium, and dark MPs in images of sea ice undergoing melt. The scheme was applied to 0.1‐m resolution Operation IceBridge Digital Mapping System imagery covering an area of ~4,000 km2. Observations of both the unconsolidated, marginal ice zone of the Beaufort/Chukchi Seas (B/C Seas) and the consolidated, multiyear ice of the central Arctic (CA) were obtained. Sea ice concentration (SIC), melt pond fraction (MPF), and pond color fraction (PCF) were derived on a per‐image basis. SIC averaged 69% in the B/C Seas and 90% in the CA. We find that both MPF and PCF are dependent on the ice type on which ponds form. MPF averaged 25% in the B/C Seas, where dark ponds dominated and had a PCF of 60%, compared to a PCF of 9% and 31%, for medium and light ponds, respectively. MPF averaged 14% in the CA, where the PCF of light ponds was 68%, compared with 16% for both medium and dark ponds. As the multiyear ice of the Arctic Ocean is replaced by a younger, more seasonal ice cover, our results suggest that MPF will increase, and MP color will darken. This would enhance the ice albedo feedback, exacerbating that already due to the multidecadal decline in summer ice extent.